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Saturday, December 10, 2011

Imagine you're on the beach and you sprint full speed into the ocean. As soon as you enter the water you slow down. Even though you're trying just as hard to run, the resistance of the water has the effect of slowing you almost as if you had become more massive.

Scientists have believed for some time that space is permeated with a field analogous to the ocean and that as sub-atomic particles move through this field it resists them. The amount of resistance is what gives these particles their mass.

The field is called the Higgs field and one of the hopes particle physicists had had for the Large Hadron Collider (LHC) was that it would detect a particle, called the Higgs Boson, which, in our analogy, is like a wave in the ocean. This would have confirmed the existence of the Higgs field and would have completed what is called the Standard Model of particle physics. Unfortunately, the prospects for finding the Higgs are dimming.

Since the Higgs is predicted by the Standard Model, the favored theory in particle physics, failure to find it will be very disappointing. It could mean having to rethink the entire discipline. New Scientist has a pretty good primer on the Higgs for those who might be interested in learning more about this exotic bit of matter:

The Large Hadron Collider finally has enough data to explore every nook and cranny where the elusive Higgs boson could be hiding. LHC physicists will announce the results of their latest hunt on Tuesday at CERN in Switzerland.

What is the Higgs boson?

It is the last undiscovered member of the standard model of particle physics, the leading theory describing how particles and forces interact. The mysterious particle is thought to give all other particles mass, but the standard model can't predict what the Higgs itself weighs.

Where might the Higgs be hiding?

The Higgs may be produced fleetingly when particles smash into each other at high speeds, and for years physicists have been looking for evidence of it at various particle colliders. They have gradually ruled out its existence at different masses, but there is still a narrow mass range, between 115 and 141 gigaelectronvolts, where the simplest version of the Higgs could take refuge.

What will LHC physicists report next week?

Rumour has it they have found hints of the Higgs at a mass of 125 gigaelectronvolts, about 133 times the mass of a proton. What is known for sure, though, is that researchers from the LHC's main detectors, ATLAS and CMS, will separately present the past year's worth of data from the proton collider. That represents more than 300 trillion high-speed particle collisions, more than twice the amount of data reported at a conference in August. That is still not enough data to be able to rule the Higgs definitively in or out, but it should be enough to show hints of the Higgs if it exists in the mass range that had previously not been scrutinised.

What if there is still no sign of the Higgs?

This time, if nothing materialises, physicists will really start giving up. "If we witness a lack of events in the full mass range, then clearly we will start disfavouring the presence of the standard model Higgs boson in LHC data," says CMS spokesperson Guido Tonelli. "To really exclude it we would need additional data. But if in this amount of data we don't see any indication that something is happening, the most likely hypothesis is that we have to look for another solution."

You can read more about these possible alternative solutions at the link.